Tow-craft for swimmer

ABSTRACT

A tow-craft for towing a swimmer through the water which includes a buoyant housing and a drive assembly carried by the housing including a gasoline engine mounted in the housing and drivingly connected to an impeller assembly mounted on the lower aft end of the housing. The impeller assembly is connected to the engine by means of a shaft and includes a three-bladed axial propeller-type impeller mounted on one end of the shaft and surrounded by a substantially cylindrically shaped tube. A plurality of inlet vanes are mounted in the tube just forward of the propeller and a plurality of outlet vanes are mounted within the tube just aft of the propeller. The tube includes an inwardly converging throat portion just aft of the propeller. In one form the buoyant housing is in the form of a molded hollow hull with a handlebar disposed across the aft end portion thereof with a throttle control mounted thereon. Another form of the buoyant housing includes a rigid hollow central portion surrounded by an inflatable floatation chamber such as a conventional inner tube. The tow-craft includes a self-bailing device and means for cooling and muffling the exhaust gases from the engine and disposing of such gases beneath the surface of the water.

Francis 1451 Oct. 9, 1973 TOW-CRAFT FOR SWIMMER [76] Inventor: AlphonsFrancis, 1121 NW. 82nd St., Oklahoma City, Okla. 73116 [22] Filed: Aug.23, 1972 [21] Appl. No.: 282,923

Foreign Application Priority Data v@ 111261271 r t ita 40 9 ,4/ 521 US.Cl ..115/6.1,115/11, 114/183 [51 1111. C1. B63b 21/56 [58] Field 61Search 115/6.1, 6, 11, 14,

[56 References Cited UNITED STATES PATENTS 2,708,759 5/1955 Strawnll5/6.1 3,623,447 ll/l97l Jacobson 115/70 3,369,518 2/1968 Jacobson115/70 3,426,724 2/1969 Jacobson 115/70 3,324,822 6/1967 Carter 115/703,112,610 12/1963 Jerger 115/16 3,613,630 10/1971 Jacuui 114/1841,470,191 10/1923 Reidm; 114/183 R 2,733,679 2/1956 Winkelman et al..1'14/183 R 2,343,313 3/1944 Maynes 9/1 Primary Examiner-Milton BuchlerAssistant Examiner- E. R. Kazenske Attorney-Jerry J. Dunlap etal.

ABSTRACT A tow-craft for towing a swimmer through the water whichincludes a buoyant housing and a drive assembly carried by the housingincluding a gasoline engine mounted in the housing and drivinglyconnected to an impeller assembly mounted on the lower aft end of thehousing. The impeller assembly is connected to the engine by means of ashaft and includes a three-bladed axial propeller-type impeller mountedon one end of the shaft and surrounded by a substantially cylindricallyshaped tube. A plurality of inlet vanes are mounted in the tube justforward of the propeller and a plurality of outlet vanes are mountedwithin the tube just aft of the propeller. The tube includes an inwardlyconverging throat portion just aft of the propeller. In one form thebuoyant housing is in the form of a molded hollow hull with a handlebardisposed across the aft end portion thereof with a throttle controlmounted thereon. Another form of the buoyant housing includes a rigidhollow central portion surrounded by an inflatable floatation chambersuch as a conventional inner tube. The tow-craft includes a self-bailingdevice and means for cooling and muffling the exhaust gases from theengine and disposing of such gases beneath the surface of the water.

10 Claims, 14 Drawing Figures PATENTEUUCT ems v 3,763,817

' sum 1m 3 PAIENIE-D 3,763,817

SHEFT 20% 3 1 rowcnxrr FOR SWIMMER BACKGROUND OF THE INVENTION not byway of limitaton, to drive units for aquatic towcraft of the typesuitable for towing a swimmer through the water.

2. Description of the Prior Art The prior art contains many teachings ofaquatic towcraft for towing swimmers through the water. The prior arttow-craft have generally displayed relatively poor performance due tothe difficulty of providing sufficient thrust fortowing a swimmer. Thesize and weight limitations of such tow-craft requires the use oflightweight engines having relatively small exterior dimensions. Suchengines provide limited power for propelling'tow-craft.

The performance of the known tow-craft is further limited by the meansemployed for converting the power output of the engine to thrust forpropelling the towcraft. Various schemes such as conventional propellersand pumps have been employed with limited success. Conventionalpropellers have been found to be inefficient due to cavitation losseswhile the pumps have been less than satisfactory due to the great powerloss in the pump mechanism. The relative inefficiency of these twopropulsion means presents an extreme problem when dealing with theinherent low power output of the available engines suitable for drivingsuch tow-craft. Another disadvantage of the use of conventionalpropellers is the inherent danger presented by such propellers toswimmers in the immediate area of the tow-craft.

The known tow-craft have generally been limited by the relatively largeoverall size required in order to provide sufficient flotation tosupport the craft if one or more swimmers might be using the craft. Thislimitation restricts the portability of such tow-craft and provides adistinct limitation on the potential uses for such tow-craft.

SUMMARY OF THE INVENTION The present invention, contemplates a tow-craftfor towing a swimmer through the water which includes a buoyant housinghaving a forward end portion and an aft end portion, a drive assemblycarried by the housing, handle means mounted on the aft end portion ofthe housing for receiving the grasp of a swimmer to be towed, andcontrol means mounted on the handle. The drive assembly includes enginemeans disposed within the housing for providing driving power for thetowcraft, rotary shaft means connected to the engine means and havingone end portion thereof extending through the aft end portion of thehousing for transmit ting driving power from the engine means, andimpeller means carried on the lower aft exterior of the housing anddrivingly connected to the shaft means for propelling the tow-craft. Theimpeller means includes an axial drive impeller rigidly secured to oneend portion of the shaft means, a substantiallycylindrically shapedtube, having forward and aft end portions, disposed substantiallycoaxially with the axis of rotation of the axial drive impeller andencircling the axial drive impeller, a plurality of substantiallylongitudinally aligned circumferentially spaced vanes each extendingradially inwardly from the inner periphery of the tube toward the shaftmeans intermediate the axial drive impeller and the forward endportion'of the tube. The impeller means further includes an inwardlyconverging throat portion substantially coaxially aligned with the axisof rotation of the axial drive impeller carried within the tubeintermediate the axial drive impeller and the aft end portion of thetube, and a plurality of substantially longitudinally aligned andcircumferentially spaced outlet vanes each extending radially inwardlyfrom the periphery of the throat portion toward the axis of rotation ofthe axial drive impeller. The tow-craft also includes first conduitmeans interconnecting the engine means and the throat portion of thetube for conducting exhaust gases from the engine means to the interiorof the throat portion wherein the exhaust gases are released through theaft end portion of the tube.

An object of the present invention is to provide a tow-craft for towinga swimmer having increased efficiency and performance.

Another object of the present invention is to provide a tow-craft havinga drive unit of improved efficiency.

An additional object of the present invention is to provide a tow-crafthaving a drive unit adapted to emit exhaust gases therefrom below andbeyond a swimmer.

A further object of this present invention is to provide atow-crafthaving small physical size, light weight and improvedportability.

A still further object of the present invention is to provide atow-craft which is economical in construction and operation.

Other objects and advantages of the present invention will be evidentfrom the following detailed description when read in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the tow-craftof the present invention.

FIG. 2 is a cross-sectional view of the two-craft of the presentinvention taken along line 22 of FIG. 1.

FIG. 3 is a side elevation view of the two-craft of the presentinvention.

N along line 77 of FIG. 5 to more clearly illustrate the construction ofthe impeller assembly.

FIG. 8 is an enlarged plan view taken along line 8--8 of FIG. 5 to moreclearly illustrate the construction of the impeller assembly.

FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 8 to moreclearly illustrate the construction of the impeller assembly.

FIG. 10 is an elevation view taken along line 10-10 of FIG. 8 to moreclearly illustrate the construction of the impeller assembly.

FIG. 11 is a plan view of another embodiment of the tow-craft of thepresentinvention.

FIG. 12 is a side elevation of the tow-craft of the present invention asillustrated in FIG. 11.

FIG. 13 is a cross-sectional view of the tow-craft of H0. 11 taken alongline 13--l3 of FIG. 12.

FIG. 14 is a cross-sectional view of the tow-craft of HG. ll taken alongline l4l4 of FlG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingsand to H68. 1 through in particular, the tow-craft of the presentinvention is generally designated by the reference character 10. Thetow-craft 10 generally comprises a buoyant housing or hull l2 and adrive assembly 14 mounted thereon. I

The housing 12 includes a hollow lower portion 16 and a removable coverportion 18. The housing 12 may be suitably constructed ofglass-reinforced epoxy or polyester resin. The cover portion 18 ispositioned over an opening 20 formed in the deck 22 of housing 12. Thecover portion 18 is secured to the deck 22 by means of a plurality ofsuitable clamps or fasteners 24 to close the opening 20. A suitable sealor gasket 26 is positioned between the cover portion 18 and the opening20 in the deck 22 to prevent the entrance of water into the lowerportion 16 of the housing 12.

A hand rail 28 is mounted on the deck 22 adjacent to the forward endportion 30 of the housing 12. The hand rail 28 affords a second swimmera convenient hand-hold at the forward end of the tow-craft 10.

A handlebar 32 is formed on the aft end portion 34 of the housing 12.The handlebar 32 provides the primary point of grasp for the swimmeroperating the towcraft l0. Hand-holds 36 are provided on the oppositesides of the housing 12 to provide a convenient point of grasp forcarrying the tow-craft from place to place.

The drive assembly 14 includes a gasoline powered internal combustionengine 38 disposed within the lower portion 16 of the housing 12. Thecrank shaft of the engine 38 (not shown) is aligned substantiallyparallel to the longitudinal axis of the tow-craft 10. The engine 38 ispreferably a one-cylinder air-cooled two stroke-cycle unit ofconventional design capable of developing approximately 1.3 horsepowerbetween 3,600 and 4,000 r.p.m., and having a cooling air fan (not shown)mounted in a housing 40 adjacent to the forward end portion 30 of thehousing 12. Cooling air is drawn into the housing 40 by theaforementioned fan and circulated through the engine to exit from asecond housing 42 at the opposite end of the engine 38. A gasoline tank44 is mounted within the housing 12 and is connected to the carburetor46 by a fuel line 48. The tank 44 is preferably mounted a sufficientdistance above the level of the carburetor 46 to provide gravity fuelflow through the line 48 from the tank 44 to the carburetor 46.

The engine 38 is supported within the housing 12 by means of acylindrically shaped tube 50 rigidly secured at one end thereof to thehousing 42 and having a flange 52 mounted on the opposite end thereof.The flange 52 is rigidly secured to the housing 12 by means of aplurality of bolts 54 as will be described in greater detail hereafter.

A propeller shaft 56 is rigidly secured at one end thereof to thecrankshaft of the engine 38 with the opposite end thereof extending aftwithin the cylindrically shaped tube 50 through an aperture 58 formed inthe housing 12.

An impeller assembly 60 is mounted on the aft end portion 34 of thehousing 12 in substantial coaxial alignment with the propeller shaft 56.The impeller assembly includes a cylindrically shaped tube 62 having aflange 64 rigidly secured to one end thereof. As best shown in FIG. 7,the flange 64 is fixedly secured to the housing 12 by means of thepreviously mentioned bolts 54, the bolts 54 passing through matingalinged apertures (not shown) formed in the flanges 52 and 64 and thelower portion 16 of the housing 12. A water proof seal is provided atthe aperture 58 between the flanges 52 and 64 by means of suitablegaskets 66 and 68.

A threebladed axial propeller-type impeller 66 is fixedly secured to thefree end of the propeller shaft 56. The propeller shaft 56 is rotatablysupported within the tube 62 adjacent to the impeller 66 by means of aconventional sealed bearing 68. The diameter of the hub portion of theimpeller 66 is preferably equal to the outer diameter of the tube 62 tominimize flow losses through the impeller assembly 60. The attachment ofthe impeller 66 to the propeller shaft 56 is preferably accomplished bymeans of a shear pin or set screw or other suitable means.

The impeller 66 is enclosed by a substantially cylindrically shapedtubular housing or duct 70 having a forward end portion 72 and an aftend portion 74. The forward end portion 72 extends longitudinallybetween the flange 64 and the impeller 66. Four substantiallylongitudinally aligned and eircumferentially spaced inlet vanes 76 eachextend radially inwardly from the inner periphery of the forward endportion 72 of the housing 70 toward the propeller shaft 56 and arefixedly secured to the outer periphery of the tube 62. The lowermostinlet vane 76 includes a forward extension 78 which extends to a pointadjacent to the flange 64. The function of the vanes 76 is to assureregular axial flow of water to the impeller without the water beingdisturbed by the rotation of the impeller 66. An opening 80 is formed inthe lower forward portion of the forward end portion 72 of the tubularhousing 70 to provide a water inlet to the impeller assembly 60.

The aft end portion 74 of the tubular housing 70 comprises an inwardlyconverging throat portion 82 extending aft from the impeller 66. Sixsubstantially longitudinally aligned and eircumferentially spaced outletvanes 84 extend radially inwardly from the inner periphery of the threadportion 82 toward the axis of rotation of the propeller 66. A divergingportion or diffuser 85 is formed at the outlet end of the aft endportion 74 just aft of the converging throat portion 82 and the vanes84. A tube 86 having a closed forward end portion 88 and an open aft endportion 90 is disposed within the throat portion 82 in substantialcoaxial alignment with the axis of the rotation of the impeller 66 andis rigidly supported in this position by means of the six outlet guidevanes 84 which are each rigidly secured to the outer periphery of thetube 86. The primary function of the vanes 84 is to secure regular axialflow of the water passing through the throat portion 82 from theimpeller 66 by substantially reducing the turbulence of the water.

The configuration of the aft end portion 74 is such that the velocity ofthe water driven therethrough by the rotary action of the impeller 66increases as it passes through the converging throat portion 82 andalong the outlet guide vanes 84. It has been found that the optimumincluded angle between opposite sides of the'converging throat portionlies between 12 and 17 with the preferable angle being approximately 16degrees. The preferable angle of approximately 16 degrees has been foundto provide maximum velocity of the water exiting from the impellerassembly 60 against the adverse pressure of the water immediatelyaft ofthe impeller assembly-60.

The'aft end portion 74' of the tubular housing 70 is convenientlysecured to the forward end portion 72 by means of a plurality ofthreaded screws 92 disposed about the periphery of tubular housing 70.

Exhaust gases are directed from the engine 38 through a first exhaustconduit segment 94 which is connected atone end to the exhaust port ofthe engine 38 (not shown). The opposite end of the exhaust conduitsegment '94 extends through an aperture 96 formed in the lower portion16 of the housing 12 and communicates with one end portion of a muffler98 disposed entirely outside the housing 12. A second exhaust conduitsegment 100 communicates at one end thereof with the opposite end of themuffler 98 while the opposite end portion of the exhaust conduit segment'100 extends back into the lower portion 16 of housing 12 through anaperture 102 formed therein. Suitable water-tight seals are providedbetween the exhaust conduit segments 94 and 100 and the respectiveapertures'96 and 102.

A'third-exhaust conduit segment 104 communicates at one end thereof withthe opposite end of the second exhaust conduit segment 100 and extendsupwardly within the housing 12 forming an inverted U-shaped "loop 106disposed within the cover portion 18 of the housing 12. The exhaustconduit seg'm ent 104 is routed downwardly from the U-shaped loop 106and is directed through the previously mentioned flanges 52 and64 of thedrive assembly '14 and the aperture 58 formed in the housing 12. As bestshown in FIG. 7, the

exhuast conduit segment 104 is routed from the aperture 58 along thecylindrically shaped tube 62 of the impeller assembly'60'and terminatesat its opposite end in communication with the interior of tube 86 of theimpeller assembly 60. Joints 112 and 114 are formed in'the exhaustconduit segment 104 at the aperture 58 ,and at the point of connectionbetween the forward and aft end portions 72 and 74 of the tubularhousing 70, respectively, to facilitate disassembly and the maintenanceof the impeller assembly 60. Again referring to FIG. 7,-the exhaustconduit segment 104 preferably lies in the same plane with the uppermostinlet vane 76 and the uppermost outlet vane 84 thereby minimizing anyobstruction to waterflow through the impeller assembly 60. The exhaustconduit segment 104 extends through an aperture 116 in the forward endportion 72ofthe tubular housing 70, and extends through an aperture 118formed in the aft end portion 74 of the tubular housing 70.

The previously described routing of the exhaust conduit segments 94, 100and 104 together with the muffler 98 provides for the efficient emissionof exhaust gases from the engine 38 in the propwash from the impellerassembly 60. This arrangement of the exhaust assembly also improves thefuel scavan'ging characteristics of the engine 38 by substantiallylowering the back pressure of the exhaust gases passing through thepreviously mentioned exhaust conduit segments.

The disposition of the muffler 98 outside the housing 12 provides twodesirable advantages of the present invention. The first advantage isthat the disposition of the muffler 98 under the water minimizes thenoise level within the housing 12 and provides for extremely quietoperation of the tow-craftlO. The second advantage is that the muffler98, being in contact with the water, provides for efficient heattransfer of the heat contained in the hot exhaust gases to the watersurrounding the muffler 98 thereby lowering the temperature of theexhaust gases that exit from the open aft end portion 90 of the tube 86in the'impeller assembly 60. The latter advantage is of great importancewhen it is considered that a swimmer using the tow-craft 10 ispositioned im mediately aft of the impeller assembly 60.

The dispensing of the exhaust gases from the engine 38 through the tube86 also provides two distinct ad vantages. The first advantage is thatengine exhaust noise is minimized by the emission of exhaust gasesbeneath the surface of the water. The second advantage is that theemission of the exhaust gases into the propwash from the impellerassembly causes the gases to be thoroughly mixed into the propwash andpropelled far behind the swimmer thereby eliminating the possibility ofobjectionable exhaust gases being encountered by the swimmer beingtowed.

It has been found by experimentation that in a preferred embodiment thenominal length of the impeller assembly 60 from the flange 64 to the aftend portion 74 is approximately 7% inches. The preferred nominaldiameter of the impeller assembly 60 has been found to be approximately4 inches. The optimum diameter of the three-bladed impeller 66 has beenfound to be nominally 3% inches. The optimum nominal dimensions of thethroat portion 82 have been found to be approximately 3 inches in lengthwith a maximum nominal in side diameter of slightly more than 3% inchesat a position adjacent to the impeller 66 with the throat portion 82converging to a nominal mimimum inside diameter of approximately 2%inches at the aft end portion 74.

While it has been found that the optimum number of inlet and outletvanes 76 and 84 are as specifically called for hereinbefore, it will bereadily apparent to those skilled in the art that other numbers andarrangements of vanes may be utilized in practicing the presentinvention.

its lowermost end portion 122 positioned in the lowermost portion of thelower portion 16 in the housing 12. The tube extends upwardly therefromforming an inverted U-shaped portion 124 disposed within the coverportion 18 of the housing 12. The tube 120 is routed downwardly from theU-shaped portion 124 and out through the flanges 52 and 64 of the driveassembly 14 and the aperture 58 formed in the housing 12 along the tubes50 and 62 to a point of termination at its opposite end portion justforward of the impeller 66 in the impeller assembly 60 as best shown inFIG. 7. A joint 128 is formed in the tube 120 between the flanges 52 and64 to facilitate the disassembly of the impeller assembly 60 from theremainder of the drive assembly 14 and the housing 12. The positioningof the opposite end portion 126 of the self-bailing tube 120 in the lowpressure area just forward of the impeller 66 permits any waterentrained in the lowermost portion of the lower portion 16 of thehousing 12 to be drawn through the tube 120 by the action of theimpeller 66 when the engine 38 is in operation.

The inverted U-shaped portion 124 of the tube 120 and the invertedU-shaped loop 106 of the exhaust conduit segment 104 are included toprevent the entrance of water through the exhaust and self-bailing tubeswhen the engine 38 is not operating, thereby preventing flooding of thelower portion' 16 of the housing 12 or the entrance of water into theexhaust port of the engine 38.

The tow-craft 10 also includes a hand-operated throttle control lever130 mounted to the right side of the handlebar 32 and connected to thethrottle of the carburetor 46 of engine 38 by means of a bowden cable132 to provide the swimmer with means for controlling the speed of thetow-craft 10. The tow-craft 10 also includes an engine starting rope 134with a handle 136 formed on one end thereof and the opposite end thereofconnected to the engine 38. A conventional single pole double throwtoggle switch 138 is mounted on the deck 22 of the housing 12 near thehandlebar 32. The switch 138 is disposed in the primary circuit wiringof the magneto of the engine 38 thereby providing the swimmer with thefacility for shutting off the engine 38 by closing the switch 138 andthereby shunting the primary circuit of the megneto to ground. When theswitch 138 is in the open position the primary circuit is isolated fromground and the engine 38 is in condition to'be started and run.

The cover portion 18 of the housing 12 includes openings 140 formed inthe upper portion thereof 142 to provide for circulation of cooling airto the engine 38 and to supply aspiration air to the carburetor 46. Theopenings 140 are preferably formed on the aft end portion of the upperportion 142 to prevent the entrance of water into the housing 12 whichmight inadvertently splash over the forward portion of the housing 12.

As shown in FIGS. 8 and 9, it may be desirable to form the aft endportion 74 of the tubular housing 70 such that the longitudinal axisthereofis offset from the axis of rotation of the impeller 66 at anangle 144 as shown in FIG. 8. The angle 144 may vary between and 20 andis intended to provide an inherent tendency' of the tow-craft 20 tocircle in the immediate area of a swimmer who might lose his grip on thehandlebar 32 of the tow-craft 10. The angle 144 of the aft end portion74 is preferably in the direction of the muffler 98. This allows theinherent drag of the muffler 98 to supplement the angled thrust of theimpeller assembly 60 to achieve the aforementioned circling tendency ofthe tow-craft l0.

OPERATION OF THE PREFERRED EMBODIMENT In operation a swimmer places thetow-craft in the water with the impeller assembly 60 submerged beneaththe surface thereof. The swimmer then grasps the handle 136 of thestarting rope 134 and pulls the rope 134 to start the engine 38. Theswimmer then grasps the handlebar 32 with both hands with his right handon the throttle control lever 130. By squeezing the throttle controllever 130 downwardly against the handlebar 32 the throttle on thecarburetor 46 is opened and the engine 38 achieves operating speed.

Water is drawn into the impeller assembly 60 through the opening formedin the forward end portion 72 of the tubular housing 70 by the rotatingthree-bladed impeller 66. Water drawn into the impeller assembly 60 isforced by the impeller 66 through the throat portion 82 formed in theaft end portion 74 of the tubular housing 70 thereby providing forwardthrust to the tow-craft 10 sufficient to tow the swimmer along throughthe water.

In the event the tow-craft 10 is to be used for lifesaving purposes, theswimmer being rescued can grasp the handrail 28 or either of the handholds 36 and be towed along by the tow-craft 10 along with the rescuingswimmer. When utilizing the handrail 28, the swimmer being rescuedshould grasp the handrail 28 with both hands while facing the forwardend portion 30 of the housing 12. As the tow-craft 10 is propelledforward the rescued swimmer should trail his legs under the housing 12toward the rescuing swimmer and will be conveyed through the water backfirst.

DESCRIPTION AND EMBODIMENT OF FIGS. 11, 12, 13 AND 14 FIGS. 11 through14 illustrate an alternate embodiment of the tow-craft of the presentinvention which is generally designated by the reference character 150.The tow-craft includes numerous elements previously described for thetow-craft 10, which elements will be accorded the same referencecharacters usd hereinbefore.

The tow-craft 150 generally comprises a buoyant housing or hull 152 andthe drive assembly 14, previously described in detail above. The housing152 includes a relatively rigid inner portion 154 of hollow constructionand a relatively flexible air-inflatable flotation chamber 156 disposedaround the periphery of the inner portion 154. The inner portion 154 ofthe housing 152 includes a hollow lower portion 158 and a removablecover portion 160. The inner portion 154 1 may be suitably constructedof glass-reinforced epoxy or polyester resin. The cover portion 160 ispositioned over an opening 162 formed in the upper portion 164 of thehollow lower portion 158. The cover portion 160 is secured to the upperportion 164 of the lower portion 158 by means of a plurality of suitableclamps or fasteners 166 to close the opening 162. A suitable seal orgasket 168 is positioned between the cover portion 160 and the opening162 to prevent the entrance of water into the rigid inner portion 154 ofthe buoyant housing 152.

A handlebar 170 is formed on the aft end portion 172 of the hollow lowerportion 158 of the housing 152. The handlebar 170 provides the primarypoint of grasp for the swimmer operating the tow-craft 150. Thehandlebar 170 is adapted to pivot about its point of connection with therigid inner portion 154 along a substantially horizontal axis to afolded stowed position as shown by the dashed lines in FIGS. 11 and 12.

v The inflatable flotation chamber 156 is disposed about and received ina circumferential recess 174 formed in the outer periphery of the innerportion 154 of the buoyant housing 152. The flotation chamber 156 isconveniently equipped with a conventional valve stem and core (notshown) to facilitate the inflation of the chamber 156 by conventionalair pump means. The flotation chamber 156 may advantageously be in theform of a conventional automobile or truck tire inner tube or speciallyfabricated of suitable flexible airtight material such as polyurethaneor rubber coated nylon cloth or the like.

As will be readily apparent, when the flotation chamber 156 is properlypositioned in the recess 174 and fully inflated, the flotation chamber156 will be rigidly secured to the rigid inner portion 154 of thebuoyant housing 152. The installation of the flotation chamber 156 onthe rigid inner portion 154 is quite similar to the mounting of anautomobile inner tube to the rim of an automobile wheel.

The mounting of the drive assembly 14 in the buoyant housing 152 isidentical to that previously described for the mounting thereof in thehousing 12 of the towcraft l and, therefore, need not be described indetail again.

The tow-craft 150 also includes a system of exhaust conduits and muffleras well as a self-bailing device. The arrangement of the exhaustconduits and muffler and self-bailing device of the tow-craft 150 isalso identical to the arrangement described previously for the tow-craft10 and therefore need not be described in detail again.

The tow-craft 150 includes a hand-operated throttle control lever 176mounted on the right side of the handle-bar 170 and connected to thethrottle of the carburetor 46 of the engine 38 by means of a bowdencable 178 to provide the swimmer with means for controlling the speed ofthe tow-craft 150. The tow-craft 150 also includes an engine startingrope 180 with a handle 182 formed on one end thereof and the oppositeend thereof connected to the engine 38. A conventional singlepole-double throw toggle switch 184 is mounted on the rigid innerportion 154 of the housing 152 near the handle bar 170 by provide theswimmer with means for shutting off the engine 38. The installation andfunction of the switch 184 is identical to that previously described indetail above for the switch 138 and, therefore, will not be described indetail again.

The cover portion 160 of the housing 152 includes openings 186 formed inthe upper portion thereof 188 to provide for circulation of cooling airto the engine 38 and to supply aspiration air to the carburetor 46. Thehousing 152 is also equipped with a duct 190 communicating between theair fan (not shown) mounted in the housing 40 of the engine 38 and oneof the openings 186 to provide cooling air directly from the respectiveopening 186 to the engine 38.

As noted above, the handlebar 170 may be pivoted about a horizontal axisrelative to the housing 152. This capability permits the handlebar 170to be folded into .a stowed position indicated by the dashed lines inFIGS.

1 1 and 12 when the flotation chamber 156 has been deflated and removedfrom the inner portion 154 of the housing 152. Sufficient storage space192 is provided within the inner portion 154 of the housing 152 to stowthe deflated flotation chamber 156 during transportation and storage ofthe tow-craft 150.

OPERATION OF THE EMBODIMENT OF FIGS. ll, l2, 13 AND 14 ventional airpump. When the flotation chamber 156 is fully inflated, the tow-craft isthen placed in the water and is operated as previously described indetail for the tow-craft 10.

The tow-craft 150 may be placed in condition for storage ortransportation by deflating the flotation chamber 156 and placing theflotation chamber 156 in the storage space 192 within the housing 152and folding the handlebar back to its stowed position as indicated bythe dashed lines in FIGS. 11 and 12.

It is believed apparent that the various embodiments of the presentinvention attain the objectives set forth herein. Changes may be made inthe arrangement or combination of parts or elements shown in thedrawings and described in the specification without departing from thespirit and scope of the invention as defined in the following claims.

What is claimed is:

1. A tow-craft for towing a swimmer through the water, comprising:

a buoyant housing having a forward end portion and an aft end portion;

a drive assembly carried by said housing and includ-- ing: engine meansdisposed within said housing for providing driving power for saidtow-craft; rotary shaft means connected to said engine means and havingone end portion thereof extending therefrom through the aft end portionof said housing for transmitting driving power from said engine means;impeller means carried on the lower aft exterior of said housing anddrivingly connected to said shaft means for propelling said tow-craft,said impeller means including:

an axial drive impeller rigidly secured to the one end portion of saidshaft means;

a substantially cylindrically shaped tube disposed substantiallycoaxially with the axis of rotation of said axial drive impeller andencircling said axial drive impeller, said tube having a forward endportion and an aft end portion;

a plurality of substantially longitudinally aligned andcircumferentially spaced inlet vanes each extending radially inwardlyfrom the inner periphery of said tube toward said shaft meansintermediate said axial drive impeller and the forward end portion ofsaid tube;

an inwardly converging throat portion substantially coaxially alignedwith the axis of rotation of said axial drive impeller carried withinsaid tube intermediate said axial drive impeller and the aft end portionof said tube;

a plurality of substantially longitudinally aligned andcircumferentially spaced outlet vanes each extending radially inwardlyfrom the inner periphery of said throat portion toward the axis ofrotation of said axial drive impeller;

handle means mounted on the aft end portion of said housing forreceiving the grasp of the swimmer to be towed;

control means mounted on said handle means and operatively connected tosaid engine means for controlling the speed of said tow-craft; and

first conduit means interconnecting said engine means and said throatportion for conducting exhaust gases from said engine means to theinterior of said throat portion wherein the exhaust gases are releasedthrough the aft end portion of said tube.

2. A tow-craft as defined in claim 1 characterized further to include:

second conduit means interconnecting the lowermost portion of theinterior of said buoyant housing and said impeller means for removingtherethrough water which may become entrained in the lowermost portionof said housing.

3. A tow-craft as defined in claim 1 wherein said first conduit means ischaracterized further to include:

a first segment having a first end thereof in communication with theexhaust port of said engine means and having the second end thereofextending outwardly through the lower portion of said buoyant housing;

muffler means having an inlet and an outlet and disposed without saidbuoyant housing beneath the surface of the water for muffling andcooling exhaust gases from the engine means with the inlet thereof incommunication with the second end of said first segment;

a second segment having a first end thereof in communication with theoutlet of said muffler means and having the second end thereof extendinginwardly through the lower portion of said buoyant housing; and

a third segment having a first end thereof in communication with thesecond end of said second segment and forming an inverted U-shaped loopwithin said housing and having a second end thereof in communicationwith said throat portion of said impeller means.

4. A tow-craft as defined in claim 1 wherein the longitudinal axis ofsaid inwardly converging throat portion is inclined at an angle slightlyto one side with respect to the axis of rotation of said axial driveimpeller, and wherein said outlet vanes are substantially longitudinallyaligned with the longitudinal axis of said throat portion.

5. A tow-craft as defined in claim 1 wherein said buoyant housing ischaracterized further to include:

a rigid inner portion of hollow construction;

an air-inflatable flotation chamber disposed around the periphery ofsaid inner portion; and

means carried by said inner portion for securing said flotation chamberto the periphery of said inner portion.

6. A tow-craft as defined in claim 5 wherein said flotation chamber istoroidal in shape and is received in a circumferential groove formed inthe periphery of said inner portion of said buoyant housing.

7. A tow-craft as defined in claim 6 wherein said flotation chamber is aconventional rubber pneumatic tire innertube.

8. A tow-craft as defined in claim 6 characterized further to include:

second conduit means interconnecting the lowermost portion of theinterior of the inner portion of said buoyant housing and said impellermeans for removing therethrough water which may become entrained in thelowermost portion of the inner portion of said housing.

9. A tow-craft as defined in claim 8 wherein said first conduit means ischaracterized further to include:

a first segment having a first end thereof in communication with theexhaust port of said engine means and having the second end thereofextending outwardly through the lower portion of the inner portion ofsaid buoyant housing;

muffler means having an inlet and an outlet and disposed without saidinner portion of said buoyant housing beneath the surface of the waterfor muffling and cooling exhaust gases from the engine means with theinlet thereof in communication with the second end of said firstsegment;

a second segment having a first end thereof in communication with theoutlet of said muffler means and having the second end thereof extendinginwardly through the lower portion of said inner portion of said buoyanthousing; and

a third segment having a first end thereof in communication therewiththe second end of said second segment and forming an inverted U-shapedloop within said inner portion of said housing and having a second endthereof in communication with said throat portion of said impellermeans.

10. A tow-craft as defined in claim 9 wherein the longitudinal axis ofsaid inwardly converging throat portion is inclined at an angle slightlyto one side with respect to the axis of rotation of said axial driveimpeller, wherein said outlet vanes are substantially longitudinallyaligned with the longitudinal axis of said throat portion.

mg UNITE STATES PATENT OFFlCE CERTll lQAE @F CQRECHON P en 37638l7 DatedOctober 9. 1973 .Inv n fl A lnhons Francis It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

F In the printed specification, column 4-, line 47 .7

after "the" and before "portion" the word "thread" should be --throat-.,In column 4, line .54, after "of" and before "rotation" delete -the. Incolumn 5, line 38, before "conduit" the word "exhuast" should be-exhaust--. In column 7, line 48, after "tow-craft" the referencecharacter "20" should be -l0--. In column 8, line 29, after "characters"change "usd" to -used---.

Signed and sealed this 12th day of February 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,LIR. Attestin CQ'MARSHALL DANN g lcer Commissioner ofPatents

2. A tow-craft as defined in claim 1 characterized further to include:second conduit means interconnecting the lowermost portion of theinterior of said buoyant housing and said impeller means for removingtherethrough water which may become entrained in the lowermost portionof said housing.
 3. A tow-craft as defined in claim 1 wherein said firstconduit means is characterized further to include: a first segmenthaving a first end thereof in communication with the exhaust port ofsaid engine means and having the second End thereof extending outwardlythrough the lower portion of said buoyant housing; muffler means havingan inlet and an outlet and disposed without said buoyant housing beneaththe surface of the water for muffling and cooling exhaust gases from theengine means with the inlet thereof in communication with the second endof said first segment; a second segment having a first end thereof incommunication with the outlet of said muffler means and having thesecond end thereof extending inwardly through the lower portion of saidbuoyant housing; and a third segment having a first end thereof incommunication with the second end of said second segment and forming aninverted U-shaped loop within said housing and having a second endthereof in communication with said throat portion of said impellermeans.
 4. A tow-craft as defined in claim 1 wherein the longitudinalaxis of said inwardly converging throat portion is inclined at an angleslightly to one side with respect to the axis of rotation of said axialdrive impeller, and wherein said outlet vanes are substantiallylongitudinally aligned with the longitudinal axis of said throatportion.
 5. A tow-craft as defined in claim 1 wherein said buoyanthousing is characterized further to include: a rigid inner portion ofhollow construction; an air-inflatable flotation chamber disposed aroundthe periphery of said inner portion; and means carried by said innerportion for securing said flotation chamber to the periphery of saidinner portion.
 6. A tow-craft as defined in claim 5 wherein saidflotation chamber is toroidal in shape and is received in acircumferential groove formed in the periphery of said inner portion ofsaid buoyant housing.
 7. A tow-craft as defined in claim 6 wherein saidflotation chamber is a conventional rubber pneumatic tire innertube. 8.A tow-craft as defined in claim 6 characterized further to include:second conduit means interconnecting the lowermost portion of theinterior of the inner portion of said buoyant housing and said impellermeans for removing therethrough water which may become entrained in thelowermost portion of the inner portion of said housing.
 9. A tow-craftas defined in claim 8 wherein said first conduit means is characterizedfurther to include: a first segment having a first end thereof incommunication with the exhaust port of said engine means and having thesecond end thereof extending outwardly through the lower portion of theinner portion of said buoyant housing; muffler means having an inlet andan outlet and disposed without said inner portion of said buoyanthousing beneath the surface of the water for muffling and coolingexhaust gases from the engine means with the inlet thereof incommunication with the second end of said first segment; a secondsegment having a first end thereof in communication with the outlet ofsaid muffler means and having the second end thereof extending inwardlythrough the lower portion of said inner portion of said buoyant housing;and a third segment having a first end thereof in communicationtherewith the second end of said second segment and forming an invertedU-shaped loop within said inner portion of said housing and having asecond end thereof in communication with said throat portion of saidimpeller means.
 10. A tow-craft as defined in claim 9 wherein thelongitudinal axis of said inwardly converging throat portion is inclinedat an angle slightly to one side with respect to the axis of rotation ofsaid axial drive impeller, wherein said outlet vanes are substantiallylongitudinally aligned with the longitudinal axis of said throatportion.